Elevator control system



May 12, 1936 A. PlNTO ET AL ELEVATOR CONTROL SYSTEM Fil ed May 4, 1935 3Sheds-Sheet 1 May 12, 1936 A. PINTO ET AL 2,040,134

ELEVATOR CONTROL SYSTEM Filed May 4, 1935 s Sheets-Sheet 2 I34 fi 30: WBP 6F I53 52 "WW 1&3 will ikjlfifl LU Z5 r25!)- I l 5 151% G Ll) 25.2 h4 5| 264 M can; (E a VW INVENTORS BY ATTORNEY May 12, 1936 A. PINTO ETAL ELEVATOR CQNTROL SYSTEM Filed May 4, 1935 3 Sheets-Sheeti ASR 40 ilk(P NV RS I. ENTO ATTORNEY but do not wish for various Patented May 12,1936- ELEVATOR CONTROL SYSTEM Anthony Pinto, New Rochelle, and RaymondAlonzo Waite, Yonkers, N. Y., assi'gnors to Otis Elevator Company,ration of New Jersey New York, N. Y., a corpo- Application May 4, 1935,Serial No. 19,766 25 Claims. 1'72152)' The invention relates to controlsystems for elevators.-

Various improvements have been made from time to time in the operationof elevators. Among such improvements is the mechanism for bringing theelevator car toan exact level with the desired landing in stopping,regardless of whether the car underruns or overruns the landing. suchmechanism usually being referred to as self levelling mechanism. Therehave' been many elevators installed since the advent of self levellingwhich are not provided with this improvement. Many owners of suchinstallations, as well as of installations made prior to levelling, aredesirous of hav-= ing elevators equipped with levelling apparatusreasons to install a complete new elevator system. In many of theseinstances, the elevators are operated on direct current under what isusually termed resistance control, i. e., an installation in which theelevator car is started by connecting the hoisting motor armature to thesource in series with resistance and the resistance cut out to bring thecar up to full speed, and in which the car is slowed down by includingresistance in series with the armature and additional resistance acrossthe armature and cutting this additional resistance out of circuit. Itis particularly to such type of control system for elevators that thepresent invention is applicable although it is useful in connection withcertain other arrangements and can be applied to new installations.

The invention involves the provision of self levelling mechanism inresistance control elevator installations.

One feature of the invention is to utilize a direct current generator tosupply current at a low voltage to the armature of the hoisting motor ofa resistance control installation during the levelling operation.

Another feature is to have the generator in operation prior to thelevelling operation but to excite the generator separately excited fieldwinding only for the levelling operation.

Another feature is to utilize a compound wound generator and to renderthe series field winding of the generator effective during levelling.

Still another feature is to connect the generator armature in thecircuit of the hoisting motor armature during full speed operation ofthe car and for rendering the generator series field winding effectiveduring such full speed operation.

Other features and advantages will become apparent from thespecification taken in connec- 'motor field.

tion with the accompanying drawings and the subjoined claims.

The invention may be carried out in various ways. The generator may bedriven all the time the elevator car is in service or for less periodsas 5 for example only while the car is running. The generator armaturemay be connected permanently in series with the hoisting motor armatureor disconnected at times but connected to the hoisting motor armaturefor the levelling operation. For the levelling operation, the hoistingmotor armature is disconnected from the source and connected across thearmature of the generator and the separately excited field winding ofthe generator is connected to the source to cause the generator tosupply current to the hoisting motor armature to bring the car to thefioor level.

In the drawings:-

Figure 1 is a schematic wiring diagram of an elevator control systemembodying the invention;

Figure 2 is a fragmental schematic wiring diagram of a portion of theelevator system exemplified by Figure 1, illustrating particularly theconnections for the generator; and

Figure 3 is a wiring diagram, similar to Figure 2-, illustratingvariations which may be made in the circuits.

Referring first to Figure 1, certain parts of the elevator controlsystem have been omitted from the wiring. diagram in the interest ofsimplification. This figure is a modified form of straight in which theoperating connections between the contacts of the switches and theiroperating mag- 5 nets are indicated by dot and dash lines. Parts of thesystem, particularly the coils and contacts of the switchesemployedtherein, may not be in the preferred points in the circuits,certain changes being made in order to make the type of wiring diagramemployed as simpleas possible.

The elevator hoisting motor has its armature designated l l and itsfield winding l2. The hoisting motor is provided with a startingresistance, '45

arrangedin steps I3, l4, i5, i6, and I1, and a slow down or by-passresistance arranged in steps I8, 20, and 2|. 22 is a dischargeresistance for the hoisting motor field winding While 23 is a resistancefor controlling the strength of the hoisting 24 and 25 are the directcurrent supply mains for applying power to the hoisting motor under carswitch control. 26 is a double pole knife switch for controlling theconnection of the system to the supply mains. To suit the type ofdiagram employed, the blades of this switch'are shown separated.

The driving motor for the generator which applies power to the hoistingmotor for the levelling operation has its armature designated 21, itsseries held winding 28, and its separately excited fleld winding ll. Thearmature of the generator is designated 3!, its series tleld winding 32,and

its separately excited field winding 1:. A resistance 34 is arranged inshunt to the generator series field winding. A resistance 38 is providedfor controlling the strength of the generator field. Four additionalresistances 3B, 31, I8, and it are provided for controlling the strengthof the gen erator ileld. A resistance arranged in steps l4, l8, and 48is provided for controlling the voltage applied to the armature of thedriving motor.

l1 and I. are the up slow speed contacts and the down slow speedcontacts respectively of the levelling switch, the levelling switch upand down fast speed contacts being designated 50 and 5! respectively. 52is the armature and B3 is the fleld winding 0! the motor 54 for movingthe rollers of the levelling switch into position to clear the levellingcams.

I! is the release coil for the elevator motor electromagnetic brake.This coil is provided with discharge resistances I6 and 51 forcontrolling the application of the brake during stopping. The car switchis designated as a whole by the numeral I. II is the safety switch inthe car. Other safety devices are indicated by legend. M is the gatecontacts while 2 designates door contacts, only one pair of doorcontacts being illustrated as indicative 0! door contacts for eachhatchway door, all these door contacts being arranged in seriesrelation.

The electromagnetic switches have been designated as follows:

AIL-Auxiliary levelling switch B-Brake switch C--Speed switch D--Downdirection switch DC-Door contact relay DH-Direction holding switchDB-Down set-up switch E-Speed switch F-Field switch Fit-Series fleldrelay G-Speed switch H--Accelerating switch nip-Inching relayJ-Acceleratlng switch K-Accelerating switch LD-Levelling down directionswitch LI -Levelling fast speed switch Lit-levelling relay LBLoad switchLII-Levelling up direction switch ILA-Driving motor accelerating switchllS- -Driving motor starting switch P--Potential switch Flt-Protectiverelay Bi -Series field switch ERA-Driving motor starting relay U-Updirection switch Us- Up set-up switch Inductance coils are designated bythe character X.

Upon the closing of the knife switch 2', the elevator motor fieldwinding i2 and actuating coil ll of potential switch P are energized,.the circuit for field winding l2 being through resistance 23 and thecircuit for coil 65 ext ndi through contacts I. of switch P, the varioussafety devices indicated by legend and including safety switch ill.Potential switch P, upon operation, engages contacts 81, 88, and I0,preparing the control and power circuits. It also separates contacts 66to insert cooling resistance in circuit with its coil, separatescontacts 12 to remove the short-circuit for step iii of the hoistingmotor armature by-pass resistance and engages contacts 59 in the circuitfor the brake release coil 55.

Assume that the system is arranged for an installation of several floorsand that the car is at rest at the first floor landing. In order tostart the car in the up direction, the operator moves the car switchinto position where its contact bar 15 bridges contacts l6, ll, 18, I0,8!), 3i, and 82. Upon contact bar 15 engaging contact '18, a circuit iscompleted for actuating coil 35 of up direction switch U and actuatingcoil 88 of brake switch B. This circuit is from supply line 24 throughthe left hand blade of switch 2|, by wire 81, through contacts 61 and 10of switch P, wire 88, by wire 89 through coil 88 of switch 3 andcontacts 30 of speed switch E, wire Si, by wire 92, through coil 85 ofswitch U, wire 93, contacts 54 of direction holding switch DH, carswitch contacts 11 and 18, by wire 95, through interlock contacts 96 ofdown direction switch D, wire 81, contacts SI of door contact relay DC,door contacts 62, gate contacts 8!, lower blade of safety switch 60,wire I00, right hand blade of switch 28, to supply line 25. If eitherthe gate or door is not closed so that the gate contacts ii or doorcontacts 62 are separated, the circuit passes through coil lill of doorcontact relay DC. This coil is of high resistance, preventing sufllcientcurrent being supplied to the coils oi switches U and B to eifect theiroperation. This current, however, is sufllcient to operate the doorcontact relay, which separates its contacts 98. This prevents thestarting of the car until the door and gate contacts are all closed andthe car switch has been returned to neutral to effect the deenergizationof coil "ii. A circuit is also completed upon contact bar I5 engagingcontact 18 for coil N2 of levelling relay LR, this circuit extendingfrom the coil to car switch contact ll through car switch contact 18.

Brake switch B, upon operation, engages contacts I84, completingcircuits for the coils I05, I08 and ll! of the driving motor startingrelay SR, up set-up switch US and down set-up switch DB, respectively.The circuit for coil III of the driving motor starting relay is frompotential switch contacts 81, wire 81, contacts I", coil l0! 0! relaySR, inductance coil Xllll, wire I", wire llfl. wire III, by wire H2,through potential switch contacts 68, the right hand blade of switch 28,to supply line 25. Coils Hi6 and Ill of the set-up switches areconnected in a circuit parallel to that of coil I05, extending throughinductance coil Xi. Coils I08 and II! are holding coils and are notstrong enough to elect the operation of their switches.

Coil I05 causes the operation of the driving motor starting relay SR,which engages its contacts III, completing a circuit for coil H6 ofdriving motor starting switch MB. This circuit is from wire 88, by wireill, through contacts Iii and coil III, wire lit, to wire H2.

The driving motor starting switch MS operates to engage contacts-III,I22, and I23 and to separate contacts I24. The separation of contactsI24 disconnects by-pass resistance I25 from across driving motorannature21. The engagement-ot contacts I2I and I23 connects the driving motorarmature and field winding to the supply lines. Thecircuit for thearmature is from wire 81, by wire I26, through contacts I2I, wire I21,through armature 21, series field 28 and resistance steps 46, 45, and M,by wire I28 through contacts I23, to wire I I2. The driving motorseparately excited field winding 30 is connected in parallel with thedriving motor armature and series field winding and thestarting'resistance. The completion of these circuits causes thestarting of the driving motor and the driving motor accelerating switchMA, coil I30 of which is connected across the motor armature byengagement of contacts I22 of switch MS, operates to engagecontacts I3Ito short-circuit resistance steps 44, 45, 46 in sequence and finally toshortcircuit series field winding 28. This brings the motor-generatorset to full speed.

Brake switch B, upon operation, also engages contacts I33, I 30 and Iand separates contacts I36. The separation of contacts I36 disconnectsdischarge resistance 51 from across the brake release coil 55. Theengagement of contacts I34 establishes the circuit for brake releasecoil 55, this circuit being from wire 81 by wire I40 through contactsI34 by wire I M through brake release coil 55, potential switch contacts69, brake switch contacts M2, wire III, to wire II2. Coil 55, upon beingenergized, acts to release the brake. Contacts I42 separate upon therelease of the brake to insert cooling resistance I39 in series with thebrake release coil.

Up direction switch U, operating at the same time as brake switch B,engages contacts I48 and I45 and separates contacts M6 and I41. ContactsI81 are interlock contacts and control the connection from supply line25 to the feed contact I68 of the car switch for downward car travel.Contacts I85, upon engagement, prepare a holding circuit for coil 85 ofthe up direction switch. The engagement of contacts i445 and separationof contacts I46 connects the=armature Ii of the elevator hoisting motorto the supply lines in such way as to cause current to be suppliedthereto in a direction to eiiect upward movement of the elevator car.The circuit for the elevator hoisting motor armature is from potentialswitch contacts 61, by wire 81 through resistance steps I3, I4, I5, I6,and 81, hold down coil I50 and contacts I SI of down direction switch D,wire I52, contacts I58 of series field switch SF, generator armature 3i,hoisting motor armature Il, up direction switch contacts I44, to wireH2.

The completion of the circuit for the elevator hoisting motor armatureand the release ofthe brake causes the elevator motor to start the carin the up direction. The engagement of contacts I35 of brake switch Bshort-circuits resistance 23 in circuit with the elevator motorseparately excited field winding I2, bringing the elevator motor fieldto full strength for the starting operation.

The levelling relay LR operates as a result of the completion of thecircuit for its coil I02 to engage its contacts I55, This completes acircuit for the levelling switch motor 54, the circuit being from wire88 by wire I56 through the armature 52 and field winding 53 of thelevelling switch motor and contacts I55 of relay LR, wire I51, wire H8,to wire 2. The levelling motor acts to move the levelling switchoperating rollers so as to clear the cams during the movement of thecar. This operation will be explained later.

The engagement of contacts I33 of brake switch 3 completes the circuitfor coil I of speed switch C and for coil I8I of up set-up switch US.This circuit is from wire 88, by wire I62, through contacts I33 ofswitch B, by wire I63 through coil I60 of switch C, and coil I6I ofswitch US, to car switch contact 19, this contact being connected bysegment 15 to car switch feed contact 18. Upset-up switch US, uponoperation, separates contacts I65 and I66 in preparation for thelevelling operation. It also engages contacts I61 to complete a circuitfor voltage coil I68 of load switch L8. This circuit is from wire 88,wire I10, by-wire I1I through contacts I61 of switch US, through coilI68 of switch LS, wire II8, to wire H2. The purpose of the load switchis served during the levelling operation, and willbe explained later. Y

Speed switch C, upon operation, engages contacts I13, I14, and I15 andseparates contacts I16. The separation of contacts I16 removes theshort-circuit for step 20 of the elevator hoisting motor by-passresistance and the engagement of contacts I15 short-circuits step I3 ofthe elevator motor starting resistance. This increases the voltageapplied to the elevator motor armature.

The engagement of contacts I14 completes a circuit for coil I19 of thedirection holding switch DH, this circuit being from wire 88 by wire I11through contacts I18 and I88 of the levelling direction switches,inductance coil X I8I, and coil I19 of direction holding switch DH,contacts I14 of switch C, wire H8, to wire H2. The direction holdingswitch upon operation, separates contacts 94 and I84. The engagement ofcontacts I83 establishes a holding circuit for coil of: up directionswitch U through contacts I45 of this switch, while the separation ofcontacts 94 breaks the initial energizing circuit for coil 85. l82 andI84 serve a similar purpose with respect to the coil of down directionswitch D for down car travel.

The engagement of circuit for coil I85 of cult is from wire 88, by wire562 through contacts I33 of switch B, contacts I13 of switch C and coilI85 of switch E to car switch contact 80, this contact being connectedby segment 15 to car switch feed contact tion, engages contacts E86,I81, and E88 and separates contacts 90 and I90. The separation ofcontacts 90 removes the short-circuit for coil I9I of levelling relayLR. Coil I 9! serves as a holding coil for the levelling relay, and itspurpose will be explained later. The engagement of contacts I81completes a circuit for the holding coil I92 of speed switch C, thiscircuit being from wire 88, wire I93, by wire I 94 through coil I92 andcontacts I81, wire I95, wire I96, wire H8, to wire H2. The purpose ofthe holding coil for switch C also will be explained later. Theseparation of contacts I 90 removes the shortcircuit for step 2i of theelevator hoisting motor by-pass resistance and the engagement ofcontacts I88 short-circuits step It of the elevator motor startingresistance. This further increases the voltage applied to the elevatormotor armature.

The engagement of contacts I86 completes a circuit for coil I91 of speedswitch G. This circuit is from wire 88 by wire I62 through contacts I33, by wire I98 through contacts I86 and coil I91, to car switch contact8|, this contact being connected by segment 15 to car switch feedconcontacts I18 completes a I82 and engages contacts I83 and Contacts 1speed switch E. This cir-,

18. Switch E, upon operatact 10. Switch G, upon operation, engagescontacts 200, 20I and 202 and separates contacts 203. The engagement ofcontacts 20l completes the circuit for the holding coil 204 of speedswitch E, this circuit being from wire 00, wire I03, wire I94, by wire205 through coil 204 and contacts 20I, wire I95, wire I96, wire IIO, towire H2. The purpose of the holding coil for switch E will be explainedlater. The separation of contacts 203 disconnects the elevator hoistingmotor by-pass resistance from across the motor armature. The engagementof contacts 202 prepares a circuit for short-circuiting step I5 theelevator hoisting motor starting resistance by contacts 206 ofaccelerating switch H. In the event that, due to load conditions, theelevator hoisting motor does not start upon the release of the brake andthe completion of the circuit for the hoisting motor armature by thedirection switch, the operation of the speed switches to graduallyincrease the voltage applied to the motor armature causes the startingof the car.

The engagement of contacts 200 completes the circuit for coil 201 ofaccelerating switch H. This circuit is from wire 00, by wire I93 throughcontacts 200, by wire I06 through coil 201, wire II8, to wire II2.Switch H, upon operation, engages contacts 206 and 200. The engagementof contacts 206 short-circuits step I oi the elevator motor startingresistance, further increasing the voltage applied to the motorarmature.

The engagement of contacts 206 completes a circuit for coil 2I0 ofaccelerating switch J. This circuit is from wire 80, by wire I93 throughcontacts 200, by wire 2 through contacts 206 and coil 2I0, wire I06,wire II8, to wire H2. Switch J, upon operation, engages contacts 2I2 and2I3. The engagement of contacts 2I2 short-circuits step I6 of theelevator motor starting resistance, further increasing the voltageapplied to the motor armature. 1

The engagement of contacts 2I0 completes a circuit for coil 2 ofaccelerating switch K. This circuit is irom wire 88, by wire I93 throughcontacts 200, contacts 2I3 and coil 2|! wire I96, wire IIB, to wire II2.Switch K, upon operation, engages contacts 2I5, 2I6 and 2". Theengagement of contacts 2 I 6 establishes a circuit through current coil2I9 of load switch LS, contacts 202 and contacts 2I2, shunting step I1of the elevator motor starting resistance. Coil 2l8 being of very lowresistance, the engagement of contacts 2I6 causes the full line voltageto be applied to the motor armature.

The engagement of contacts 2I1completes a circuit for coil 2l8 of fieldswitch F. This circuit is from wire 80, by wire I62 through contacts I33of switch B by wire 220 through coil 2l8 and contacts 2I1 to car switchcontact 82, this contact being connected by segment to car switch feedcontact 10. Switch F, upon operation, separates contacts 22I, removingthe" short-circuit for resistance '23 for the elevator separatelyexcited field winding, increasing the field strength and bringing theelevator hoisting motor up to full speed.

The engagement of contacts 2I5 oi switch K completes a circuit for coil222 of series field relay FR. This circuit is from wire 01, by wire I26through contacts I2I,contacts2|l,induetarme coil X223 and coil 222, bywire I through contacts I23, to wire II2. Relay FR, upon operation,engages contacts 224 which canpletes the circuit for coil 226 of seriesfield switch SF. This circuit is from wire 81, by wire I26 through con-"motor armature.

tacts I2I, by wire 226 through contacts I22, by wire 221 throughcontacts 220 and coil 22!, wire I20, to wire I I2. The series fieldswitch operates to separate its contacts I52, removing the shortcircuitfor series field winding 22 of the generator. This renders the generatorefiective as a series generator in series with the elevator hoistingmotor.

This arrangement provides an eiiective load compensation wherebysubstantially constant speed is obtained for full speed operation. Thegenerator acts to provide a voltage of proper polarity and of a valuewhich counteracts any tendency or the elevator motor to vary its speeddue to load conditions. For example, assume that the elevator motor islifting a heavy load. This causes positive current of high value to flowin the hoisting motor armature circuit. This current, passing throughthe series field winding, causes a high excitation of the generator.,

The generator thus generates a voltage which is added to the voltageapplied from the source 2|, 25 to the motor. Thus, any tendency of theelevator motor to decrease in speed due to increase in load isefiectively counteracted by the generator's applying an additionalvoltage to the elevator motor to maintain the speed thereof substantially constant. Similarly, should the elevator motor be lowering aheavy load so that the tendency is to overspeecl, the generator seriesfield is excited in the opposite direction by the current oi. negativevalue which flows in the hoisting motor armature circuit thereby causingthe generator to apply a voltage which opposes the line voltage andthereby counteracts the tendency of the hoisting motor to increase inspeed.

The amount of compensation provided by the generator is controlled bymeans of an adjustable resistance 34 connected across the series fieldwinding. The operation of the series field switch to render thegenerator efiective for full speed operation is delayed by means of theinductance coil X223 in series with coil 222 of the series field relay,this inductance delaying the operation of the relay after the applicatin of source voltage to the motor armature and the weakening oi. themotor field, substantially until the motor comes up to full speed. Thegenerator, with this arrangement. is rendered ineil'ective during theaccelerating period, thereby oviating any undesirable effect due toheavy accelerating currents. This permits a small generator to be used.

To stop the car, the car switch is centered as the car arrives at apredetermined distance from the landing at which it is desired that astop be made. The centering of the car switch moves segment 15 oilcontacts 82, II, 80, 18, 10, and 11. Thisbreaics the circuit for coils2l8, I91, I85, IBI, I60, and I02 of switches F, G, E, US, C, and LRrespectively.

The deenergization oi coil 2I0 of field switch 1' results in thereengagement of contacts 22I to short-circuit resistance 23 for theelevator motor field winding I2. This causes the car to slow down. Thedeenergization of coil I91 0! speed switch G results in the separationof contacts 202 to reinsert resistance steps I6, I6, and I1 in circuitwith the elevator motor armature and in the reengagement oi contacts 203to connect steps I8, 20, and 2I of the by-pass resistance across theThis causes further slow down of the elevator car.

Switch G also separates contacts 200 to deenerglze coils 201, 2I0 and2I4 of accelerating switches H, J, and K respectively. The acceleratingswitches thereupon drop out to separate contacts 206, 2I2, and 2H5, thesteps of resistances I5, I6, and I1 respectively controlled by thesecontacts having already been reinserted in the armature circuit by theseparation of contacts 202 of speed switch G. Accelerating .switch Kalso separates contacts 2I1 in the circuit for coil 2I8 of field switchF, this circuit having already been broken by. the centering of the carswitch, and separates contacts 2I5 to break the circuit for coil 222 ofseries field relay FR. The series field relay drops out to separatecontacts 224,.breaking the circuit for coil 225 of series field switchSF. This switch reengages its contacts I53 to shortcircuit the seriesfield winding 32 of the generator during the slow down period.

Speed switch E does not drop out immediately the circuit for its coilI85 is broken by the disengagement of car switch segment 15 from contact80, this switch being maintained operated by its holding coil 204. Thecircuit for this holding coil is broken by the separation of contacts20I of switch G. The breaking of this circuit, however, is delayed untilafter switch G has otherwise performed its functions upon dropping out,this delayed action being indicated by the elongation of the stationarycontacting elements of contacts 2IlI. Upon the deenergization of holdingcoil 204, switch E drops out toseparate its contacts I 86 in the circuitfor coil I91 of switch G,

this circuit having already been broken by the centering of the carswitch. It also separates contacts I88 to reinsert step I4 of thestarting resistance in circuit with the motor armature and reengagescontacts I90 to short-circuit step 2I of the by-pass resistance. Thiscauses further slow down of the car.

Switch E also reengages contacts 90 to shortcircuit coil ISI oflevelling relay LR. Coil I02 of the levelling relay having beendeenergized by the centering of the car switch, the relay is maintainedoperated up to this time by coil I9I. The deenergization of coil I91causes the levelling relay to drop out, separating its contacts I55 andthereby breaking the circuit for levelling switch motor 54. In thismanner, the operating rollers of the levelling switch are extended forengagement by the levelling cams. Referring to Figure 2, the levellingswitch motor is operatively connected to the levelling switch by meansof. an arm 230 on the motor shaft, a connecting link 23I and a lever232. In the starting operation, the motor 54 being energized, arm 230rotates, acting through link 23I and lever 232 to move the levellingswitch as a whole about a pivot. In this manner the levelling switchoperating rollers 233 and 234 are moved into position where they do notengage the levelling cams 235 and 236 during motion of the car, a stopbeing provided to determine the extent of the movement. It is to beunderstood that levelling cams are provided for each floor. Thelevelling switch is pivoted on a bracket 231 secured to. the car frame.In the stopping operation, upon the deenergization of the levellingswitch motor, a spring (not shown) moves the lever 232 and therefore thelevelling switch back into the first described position with the rollers233 and 234 extended for engagement by'the levelling cams. Each pair oflevelling contacts 41, 48, 50, and 5| comprises a stationary contact anda movable contact operated by the engagement of its corresponding rollerand levelling cam. The fast speed contacts 50 and 5I are arranged toseparate before their corresponding slow speed contacts 4! and 48 in thelevelling peration. Springs (not shown) are provided for causing theseparation of the contacts of the pairs as the levelling operation iseffected and stops are provided for determining the extent of movementof the rollers as they ride oil the levelling cams.

It will be assumed that the car has not reached the landing and that theup levelling switch operating roller 233 has notmoved onto the verticalsurface of up levelling cam 235 at the time levelling switch motor 54 isdeenergized. Switch E, by the delayed opening of its contacts I81,postpones thedropping out of switch C until after switch E has performedits functions in dropping out. The separation of contacts I81 breaks thecircuit for holding coil I 92 of switch C, which drops out to separateits contacts I13, I14, and I and to reengage its contacts I18. ContactsI13 are in the circuit for coil I85 of switch E previously broken by thecentering of the car switch. The separation of contacts I15 removes theshort-circuit for the remainder of the starting resistance for themotor, while the reengagement of contacts I16 short-circuits step 20 ofthe by-pass resistance. This causes further slow down of the elevatorcar.

The separation of contacts I14 is delayed, as 3 indicated by theelongation of the stationary contacting elements thereof. Uponseparation of these contacts, the circuit for coil I19 of directionholding switch DH is broken. Means are provided to delay the droppingout of the holding switch so as to obtain the desired retardation.Inching relay IR has its coil 240 connected across the motor armatureand its contacts 2 connected in a circuit by-passing coil I19 of switchDH. These contacts are'in engagement so that this by-pass circuit iscomplete at this time. Switch DH is maintained operated by the action ofinductance coil XI8I in series with coil "9 and the resistance connectedin this closed circuit. The values of resistance and inductance in thiscircuit are preferably such that the direction holding switch ismaintained operated until the levelling mechanism assumes control.

It will be assumed that the up levelling switch operating roller 233moves onto the vertical surface of up levelling cam 235 before directionholding switch DH drops out. The engagement of levelling switch up slowspeed contacts 41 completes a circuit for coil 242 of the levelling updirection switch LU, coil 243 of auxiliary levelling switch AL and coil244 of brake switch B. This circuit is from wire, 88, by wire 245through coil 244 and coil 243, by wire 246 through coil 242 andinterlock contacts 241 of levelling down direction switch LD andlevelling-switch contacts 41, wire 248, wire I51, wire II8, to wire II2.Contacts 250 of protective relay PR in shunt to coil 244 are separatedat this time, permitting the energization of this coil by the levellingswitch.

'Coil 25I of the protective relay is connected wire III, throughcontacts II, wire III, contacts 41, wire III, wire I", wire III, to wireIII.

'Ihe auxiliary levelling switch AL, upon operation, engages contactsIII. The purpose oi this switch will be explained later.

The levelling fast speed switch'LF, upon operation, engages contacts IIIto short-circuit the portion 0! resistance II employed to cause thelevelling operation to take place at slow speed.

The levelling up direction switch LU, upon operation, separates contacts"I and I11 and engages contacts III, III and III. Contacts III areelectrical interlocks in the circuit ior coil 2" oi levelling downdirection switch ID. The separatbli oi contacts III iorces the droppingout engagement oi contacts III and III oi the levelling up directionswitch. The circuit ior field winding II is irom wire I1,'wire III, bywire III through contacts III oi the levelling up direction switch andcontacts III oi down set-up switch DB, by wire III, through iieldwinding II by wire I", through resistance II (contacts III beingmaintained separated by holding coil III oi up set-up switch US aiterthe deenergization oi coil' III by the centering oi the car switch),contacts III oi the levelling up direction switch, by wire III throughcontacts III oi levelling iast speed switch, wire III, to wire III..Thus, upon the operation oi the levelling mechanism to bring the car tothe floor landing, the hoisting motor armature is disconnected irom themain source oi supply and is supplied with current by the generator oithe motor-generator set, the armature oi the generator and the armatureoi the hoisting motor being connected in a closed circuit due to thereengagement oi contacts III oi the up direction switch, which by-passessteps II, III, and II oi the by-pass resistance through the hold downcoils oi the direction switches and contacts III oi the down directionswitch.

With the generator separately excited iield winding II connected to the.source and with contacts III oi the levelling iast speed switch inengagement, a voltage is generated by the generator which causes theelevator motor to run at a suitable iast levelling speed in the updirection, the brake being maintained released owing to the iact thatbrake switch B is maintained operated by its coil III.

OontactsIII oi levelling up direction switch .LU are arranged inparallel with contacts III 0! accelerating switch K. The engagement oicontacts III completes the circuit ior coil III oi series ileld relayFR. This relay engages contacts III to complete the circuit ior coil IIIoi series field switch SF. which separates its contacts III to renderthe generator seriesfleld winding eflective ior the levelling operation.The operation oi the series iield relay FR is delayed by inductance coilIII in order that the current in the generator armature-elevator motorarmature circuit may adjust itseli to such value that the proper seriesfield strength ior the revelling operation is obtained.

As the car nears the landing, roller III rides oi! the vertical suriaceonto the oblique surface oi cam III. This results in the separation oiup fast speed'levelling contacts II, deenergizing actuating coil III oithe levelling fast speed relay LF. Relay LF', upon dropping out,separates its contacts III to remove the short-circuit for resistance3!. This decreases the voltage applied to separately excited ileldwinding II oi the generator, decreasing the generator voltage to a valueto cause the elevator motor to run at slow levellin speed. Shortlybeiore the car reaches an exact level with the landing, roller I33 ridesoii the oblique suriace oi cam I35, thereby separating slow speedlevelling contacts 41. This breaks the circuit for coil III oi auxiliarylevelling switch AL, coil III oi levelling up direction switch LU andcoil I of brake switch B. Thelevelling up direction switch operates itscontacts III and III to disconnect the generator separately excitedfield winding II irom the source oi supply, while brake switch Bseparates its contacts III to deenergize brake release coil II, applyingthe brake and bringing the car to a stop. At the same time switch Breengages its contacts III to connect discharge resistance II inparallel with discharge resistance II ior the brake release coil iorobtaining the desired application oi the brake shoes. Switch B alsosepar ates contacts III to reinsert resistance II in the circuit withelevator motor field winding II, reducing the voltage applied to thiswinding while the car is at rest.

The levelling up direction switch also separates its contacts III todeenergize coil III of series iield relay FR, which in turn separatesits contacts III to deenergize coil III oi series field switch SF. Theseries iield switch reengages its contacts III to short-circuitgenerator series field winding II.

Switch 13, upon dropping out, also separates contacts III to disconnectcoil III of the driving motor starting relay. and holding coil III oisetup switch US irom the source oi supply. These switches do not dropout immediately, however, relay SR being delayed by the eii'ect oiinductance coil XIII and dischargeresistance III and switch US beingdelayed by the effect of inductance coil XIII and discharge resistanceIII. The purpose oi the delay in the dropping out oi these switches willbe seen irom later description. Switch US, upon dropping out, separatescontacts III and engages contacts III and III. The separation oicontacts I" deenergizes coil III oi loadswitch LS. The reengagement ofcontacts III and III shortcircuits levelling control resistances II andII, respectively. Relay SR, upon dropping out, separates contacts III todeenergize coil III oi the driving motor starting switch MB. This switchdrops out to separate its contacts III and III, disconnecting thedriving motor oi the motorgenerator set from the source oi supply. Atthe same time, switch MS reengages contacts III to disconnect by-passresistance III across the armature II of the driving motor, bringing themotorgenerator set to a stop. Switch MS also separates contacts III,disconnecting coil III oi the driving motor accelerating switch MAacross the driving motor armature II. This switch drops out, separatingits contacts III and III in preparation ior the next operation.

In the event oi overrun, assuming in the above example that the caroverruns the floor to the extent of causing the engagement oi down slowspeed levelling contacts 48, a circuit is completed for coil 21 5 of thelevelling down direction switch. This circuit may be traced from wire88, by wire 245 through coil 244 of switch B and coil 243 of switch AL,by wire 216, through interlock contacts 21? of levelling up directionswitch LU, coil 215, contacts 48, wire 248, wire I51, wire H8, to wire Ii2.

The brake switch B engages its contacts I04, reestablishing the circuitfor the coils I05 and I06 of driving motor starting relay SR and upset-up switch US, respectively. As previously explained, these switchesare maintained operated after contacts N34 disconnect their coils fromtheir source of supply by the action of their respective inductancecoils and discharge resistance. This portion of the system is adjustedso as to maintain these switches in operated conditionduring an overrununtil the circuit for their coils is again established as a result ofthe engagement of the slow speed levelling switch contacts for returningthe car to the floor, these contacts being levelling down directionswitch contacts 48 in the example:

assumed. Thus, upon an overrun, relay SR is maintained operated,maintaining the driving motor'for the motor-generator set in operation.Also, up set-up switch US is maintained operated with its contacts I andIE5 separated.

The levelling down direction switch LD, upon operation, engages itscontacts 280 and 28I, completing a circuit for the generator sepaFatelyexcited field winding 33. This circuit may be traced from wire 81, wire253, by wire 282, through contacts 280, by 1 wire 283 through resistance36 ,(cqntacts I65 being maintained separated by the up set-up switch asabove explained), by wire 289,

through field winding 33, contacts 284 of down set-up switch DS andcontacts 28I by wire 288 through resistance 35, wire I28, to wire H2.Due to the reversal of the flow of current through field winding 33 fromthat during levelling with the car approaching the floor in the updirection, the car is caused to start in the down direction, the brakebeing lifted as a result of the engagement of contacts I34 of brakeswitch B. Since levelling fast speed switch LP is not operated,resistance 35 is included in the circuit, causing the voltage generatedby the generator to be such as to cause the hoisting motor to operatethe car at slow levelling speed. l

The levelling down direction switch LD also engages contacts 285 tocomplete a circuit for the coil 222 of the series field relay FR,contacts 285 being arranged in parallel with contacts 262 of levellingup direction switch LU. The series field relay causes the operation ofthe series field switch SF as before to remove the short-circuit for thegenerator series field winding 32. This operation is delayed by theaction of inductance coil X223, to insure that the current in thegenerator armature-motor armature circuit has fallen to a low valuebefore the series field winding is rendered effective.

As the car returns to the floor, it is stopped by the separation oflevelling switch slow speed contacts 48 in a manner similar to that forapproaching a floor in the up direction. If the overrun is great enoughto cause the engagement of levelling switch down fast speed contacts 5Ias well as contacts 48, coil 252 of the levelling fast speed switch LFis energized. As before, switch LF engages contacts 258, causing thevoltage generated to be of a value to cause the elevator motor to run atits fast levelling speed. Shortly after the car is returned to thefloor, the driving motor starting relay SR drops out, causing thediscontinuance of the operation of the motor generator set.

The starting of the car in the down direction is accomplished in amanner similar to that for starting the car in the up direction, andwill be described only briefly. ,The operator moves the car switch intoposition where segment 15 bridges contacts 286, 281, I48, 289, 290, HI,and 292. The bridging of contacts I48 and 281 completes a circuit forcoil 86 of brake switch B and coil 293 of down direction switch D. Thiscircuit maybe traced from wire 81, by wire 89, through coil 86 of brakeswitch B and contacts 98. of switch E,

wire 9|, by wire 294 through coil 293 of switch D,

contacts I82 of switch DH, contacts 281 and I 48 of the car switch, bywire 295 through interlock contacts I41 of switch U, to supply line 25as traced for coil 85 of switch U. The circuit for coil I02 of levellingrelay LR. is by way of contacts 286 of the car switch. The circuit forcoil'I 60 of speed switch C is by wire 296 through coil 291 of downset-up switch DS. The circuit for coil I85 of speed switch E is by wayof car switch contact 290 and wire 219. The circuit for coil I91 ofspeed switch G is by way of car switch contact 29I and wire 298. Thecircuit for coil 2I8 of field switch F is by way of car switch contact292 and wire 300. The down direction switch D, upon operation, engagescontacts 30I and 302 and separates contacts I5I and 96. The engagementof contacts 302 prepares the holding circuit for coil 293 of switch D,which is later completed by the engagement of contacts I84 of switch DH.The engagement of contacts 30I and the separation of contacts I5Icompletes the circuit for the armature of the elevator hoisting motorfor operating the car in the down direction. The down set-up switch DSseparates contacts 265 and 284. Further than this, the operation ofstarting the car in the down direction is the same as for starting thecar in the up direction. The slowing down and stopping of the car duringits downward travel is similar to that described for the slow down andstopping of the car during its upward travel. Such operation will not bedescribed as it is believed that it will be understood from previousdescription.

Load conditions have not been considered in the description of operationup to this point. Means are provided which are effective duringlevelling to compensate for the load on the hoisting motor. Thiscompensation is effected by means of load switch LS acting on resistancein circuit with generator field winding 33. The load switch is providedwith a current coil 2I9 and a voltage coil I68. The voltage coil isineffective to cause operation of the load switch but acts to maintainthe switch, once operated, in operated condition. The current coil isrendered effective during acceleration upon the operation of the lastaccelerating switch K. With this arrangement, the load switch operateswhen the current which flows in the current coil at the time that coilis rendered effective is at or above a predetermined value.

It will be assumed that the switch is adjusted to operate at balancedload, it being understood that the exact point at which the switchoperates is determined by the characteristics of the particularinstallation. Upon operation of the switch, it separates contacts 305and 305 and engages contacts 301 and 308, these contacts controllingresistances 38, 31, 38, and 41. The set-up switches switch contacts 305and 306 are separated while load switch contacts 301 and 300 areengaged. Also, contacts I65 and I06 of the up set-up switch US areseparated due to the fact that the car is travelling in the updirection. Under such conditions, the generator field winding circuitfor the up levelling operation does not include resistance 31 andincludes only a portion of resistance 40 as resistance 31 isshort-circuited by contacts 266 of the down set-up switch DS and all buta portion of resistance 40 is short-circuited by load switch contacts000. This gives the desired higher value oi generated E. M. F. forlifting the car and its load up to the floor.

11, under the conditions above assumed, the car overruns the floor,resistance 36 is included in the circuit with field winding 33 for thereturn operation because load switch contacts 305 and up set-up switchcontacts I66 are separated, thereby" giving a lower value of generatedE. M. F. to compensate for the load on the elevator motor now being anoverhauling one, i. e., the car and its load overbalancing thecounterweight.

If the car had been running in an up direction lightly loaded so thatthe load switch is not operated, the load is an overhauling one (the carbeing overbalanced by the counterweight) so that, with load switchcontacts 308 separated, resistance 40 is included in the generator fieldwinding circuit to provide a lower value of generated E. M. F. In caseof an overrun under such conditions, it becomes necessary to lift a load(the counterweight) to return the car to the floor so that, load switchcontacts 305 being in engagement, only a small portion of resistance 36is included in the generator field winding circuit, thereby giving ahigher value of generated E. M. F. to compensate for the load.

The action is similar for downward car travel. Assume that the car istravelling downwardly lightly loaded, which means that the elevatormotor is lifting a load. Contacts 266 and 284 of down set-up switch D5are separated because the car is travelling downwardly, while contacts305 and 306 of the load switch are separated and contacts 301 and 308 ofthe load switch are engaged, owing to the fact that the motor is liftinga load. Thus, during underrun conditions, only a'small portion ofresistance 38 is included in the generator field winding circuit to givea higher value of generated E. M. F. and during underrun conditions allof resistance 31 is included in the field winding circuit to give alower value of generated E. M. F. becausethe load for returning the carto the floor is an overhauling one. In case the car is heavily loadedduring its downward travel, the elevator motor is lowering a load, sothat the load switch is not operated. Therefore all of resistance 3B isincluded in the field winding circuit during underrun conditions whileonly a portion of resistance 31 is included in this circuit duringoverrun conditions.

Should the car, while standing at a floor, be moved downwardly from thefloor into the level ling zone, as by the taking on of a heavy load, theprotective relay PR, acts to prevent the liftmg of the braketo move thecar until the motorgenerator sethas been started and has come up to apredetermined speed. The coil 261 of the protective relay is connectedacross the driv n8 motor armature 2l so as to be subject to the counterE. M. F. of the driving motor and therefore the speed of themotor-generator set. Contacts 250 of the protective relay are connectedin shunt to coil 244 of the brake switch B. Thus, coil 244 cannot beenergized by the levelling mechanism to operate the brake switch andthus to effect the release of the brake until the driving motor has comeup to a certain speed. Additional contacts 254 on driving motoraccelerating switch MA serve a similar purpose. These contacts preventthe operation of the levelling fast speed switch LE to place a load onthe generator by short-circuiting resistance 36 under such conditions,in the event the car sags into the fast speed levelling zone, until themotor-generator set comes up to a predetermined speed, the coil I30 ofthis switch being subject to the armature 21 of the driving motor of theset. The auxiliary levelling switch AL acts under such conditions toeffect the starting of the motor-generator set.

The coil 243 of this switch is connected in a circuit common to thecoils of the levelling direction switches so as to operate the switchwhen either one of the levelling direction switches operates. Contacts259 of the auxiliary levelling switch are connected in parallel withcontacts I04 of the brake switch to cause the operation of the drivingmotor starting relay SR and thus the starting of the motor-generator setwhen the operation of thebrake switch is prevented due to coil 244 beingshort-circuited by contacts 250. Thus, should the car, while standing ata floor, sag into the levelling zone, the" motor-armature set is startedby the action of switch AL but the operation of bringing the car back tothe floor and the placing of any considerable load on the generator aredelayed until the motor-generator set attains a predetermined speed.

Should any of the safety devices operate or should the safety switch 60in the car be operated. the potential switch A is deenergized. Thisswitch, in dropping out, breaks the control circuits, causing the car tobe brought to a quick stop. Involved in this emergency stoppingoperation is the separation of contacts 69 of switch A to prevent theconnecting of resistance 51 across the brake coil, giving a hard brakingaction, and the engagement of contacts 12 of switch A to connect a smallportion of by-pass resistance across the hoisting motor armature,resistance steps I8, 20, and 2! being excluded from the by-pass circuit.

The inching relay IR, having its operating coil 240 connected across theelevator motor armature H and its contacts MI in the by-pass circuit forcoil I19 of the direction holding switch DH, acts to prevent thedirection holding switch being held in by the efiect of inductance coilXIBI unless the elevator motor is up to a certain speed. This permitsthe attendant in the car to inch the car without having to wait on anytime elements in the event that he throws his car switch too far over inperforming the inching operation.

Many of the control operations previously described are in the nature ofrefinements, and may be varied or omitted entirely. Also, the manner ofeffecting other control operations may be modified. The motor-generatorset has been described as starting up with the starting of the releasecoil is' completed by the engagement of illustrating the principles ofoperation of appli-' cants invention as exemplified by Figure 1. Themanner of starting and stopping the car is not shown as this may beaccomplished in several ways. The contacts of direction switches,however, are shown, these being designated M4, I46, ll, and 30! tocorrespond with the designations of such contacts in Figure 1. Thesecontacts are "operated in accordance with the direction of car traveldesired, as, for example, by the manipulation of a car switch or thepressing of a push button, to complete a circuit for the armature H ofthe elevator hoisting motor. The armature 3| of the generator of themotor-generatorset is included in this circuit and may be driven onlyWhile the elevator motor is in operation or all i the time the elevatoris in service or for other periods, as, for example, by maintaining theset in operation for a predetermined time interval,

after the car is stopped. The switch B for controlling theelectromagnetic brake ER is illustrated as having a coil controlled bythe levelling mechanism. The other coil of the-switch may be energizedin any suitable manner in starting, depending upon the installation. Nocontrol is illustrated for field winding ii of the hoisting motor, asthis may be arranged to suit the requirements of the particularinstallation. If desired, a full field may be maintained on the hoistingmotor so long as'the elevator car is in service.

In starting the car, the circuit for the brake contacts 534! of brakeswitch B, releasing the brake. The circuit for the hoisting motorarmature H is completed by the operation of the directionswitch'thecircuit including generator armaturetl and starting resistance SR inseries with the motor armature with by-pass'resistance BF connectedacross these armatures. The by pass resistance is increased duringacceleration and finally disconnected and the starting re-- sistance isshort-circuited in steps and finally the .armatures of the hoistingmotor and generator are connected directly to the source, bringing thehoisting motor up to full speed.

When the car is to stop at a landing, starting resistance SR isreinserted in circuit with the elevator motor armature l l and generatorarmature 3i and by-pass resistance BP is reconnected across thesearmatures and short-circuited. When the levelling mechanism takescontrol, the elevator motor armature H is disconnected from the sourceof supply and connected in a local circuit with armature 3! of thegenerator through contacts M5 and i5l of the direction switches. As thistakes place, the levelling mechanism completes the circuit forthegenerator field winding 33 to render the generator effective to applyvoltage to the elevator motor to bring the car to the landing level. Thegenerator series field winding 32 is rendered effective for thelevelling operation by the operation of switch SF so as to compensatefor load. 'When the car comes to an exact landing level, generator fieldwinding 33 is disconnected from the source and the brake is applied tobring the car to a stop.

The series field winding 32 of the generator may be controlled so as tobe rendered effective during full speed operation of the elevator motoras well as during levelling. With the series field rendered effectivefor full speed operation, the generator acts to compensate for load soas to pro- I vide substantially the same speed of the elevator I car,regardless of load. By using a generator of the proper size andcharacteristics, the series field winding may be left in during theacceleration and retardation periods. In such case, the generatorwouldact as an accentuator in that during acceleration it would act toincrease the voltage applied to the elevator motor armature as the speedin acceleration steps takes place, due to the increased current floweach time the voltage applied to the elevator motor armature isincreased.

Any suitable arrangement for controlling the circuit for the separatelyexcited field winding 33 of the generator for levelling may be employed.This includes not only the circuits but also the levelling mechanismitself. Other forms of levelling mechanism than that diagrammaticallyillustrated in this figure may be employed, a diagrammatic illustrationof one form of levelling control mechanism being made in'this figure forconvenience.

The levelling mechanism is illustrated as acting through levellingdirection switches LU and L!) for controlling, the circuits forgenerator field winding 33 and as acting through brake switch B tocontrol the action of the elevator hoisting motor brake. vIn thearrangement shown, the levelling mechanism acts through levelling fastare simplified for illustrating the principles of operation. The mannerof starting and stopping the car is not shown. The contacts of thedirec-= tion switches are designated l-ld, l lti, it'll, and till asbefore. The direction switches may be provided with a walking beam toserve as a mechani= cal interlock, in which event the back contacts ofboth direction switches cannot be closed at the same time. Sucharrangement is assumed and only contacts l5! are shown closed, on theassumption that the car has been travelling in the up direction. Thearmature ill of the generator of the motor generator set is not arrangedin the hoisting motor armature circuit. Instead it is lo cated in thecircuit for the icy-pass resistance BP. The starting resistance isarranged in two parts. The starting resistance SSR controlled by thespeed switches is arranged in the armatiu'e circuit inside the directionswitch contacts, while the resistance ASR controlled by the acceleratingswitches is arranged in the armature circuit outside the directionswitch contacts. This arrangement, as well as the arrangement of Figures1 and '2, is found in many existing elevator instal lations.

The brake BR is released in starting the car by the completion of thecircuit for the brake release slstance B? and generator armature ii areconnectedaerossthearmature ll otthe hoisting motor and startingresistances SSH. and ASR' are connected in series therewith. The by-passresistance is increased during acceleration of the hoisting motor.Disconnection oi the by-pass re sistance also disconnects generatorarmature II from across the hoistingmotor armature. The seriesresistances SSH. and ASR are decreased during acceleration and finallyarmature II or the hoisting motor is connected directly to the source ofpower. This brings the elevator car up to lull speed.

In slowing down and stopping the car at a landing, starting resistanceASR is reinserted in circuit with the elevator motor armature II andthen starting resistance SSR is reinserted in the motor armaturecircuit. The by-pass resistance BP and the generator armature 3| areconnected across the motor armature at the time starting resistance SSRis reinserted in circuit, and the value of the by-pass resistance isdecreased as the short-circuit for the steps of starting resistance SSRis removed. When the levelling mechanism takes control, the elevatormotor armature is disconnected from the source of supply and connectedin the local circuit with armature ii of the generator through con--tacts 6, closed in response to the operating of the levelling mechanism.The levelling mechanism also causes the closure of contacts 3H, whichby-pass contacts 315 to maintain the brake release coil energized andthe brake rcleased. As this takes place, the levelling mechanismcompletes the circuit lot the generator field winding 33 to render thegenerator effective to apply voltage to the elevator motor to bring thecar to the landing level. The generator series field winding 32 isrendered effective to compensate for load during levelling by theoperation of switch SF. when the car comes to on exact landing level,generator field winding 33 is disconnected from the source and the brakeis applied to bring the car to a stop.

The contacts ll, 48, 50, and 5| of the levelling switching mechanism areillustrated as acting through electromagnetic switches LB, LU, LD, andLP to control the levelling of the car, con tacts iii and 3 beingprovided on switch LB.

The arrangement of the generator armature in the by-pass circuit has theadvantage that the armature is not subjected to the peaks oi startingcurrent and therefore a smaller generator may be employed. However, thisarrangement lacks the advantage of the generator providing loadcompensation for full speed operation, as with the generator armaturearranged in series with the motor armature as in the case of Figures 1and 2. In case of change-over installations, the character of theinstallation may determine the point where the generator armature isplaced in the circuits.

Circuits are also shownin Figure 3 for con trolling the starting andstopping of the driving motor for the motor-generator set. In thearrangement shown, the motor-generator set is arranged so that it may bemaintained in operation all the time the car is in service, a manualswitch SS being arranged in the control circuits for the driving motorto start and stop the driving motor at will.

The switch SS comprises a bridge member 320 which, when turnedcounterclockwise, bridges contacts "I to complete a circuit for coil 32201' driving motor startinfl switch MS. This switch engages contacts 323and 314. The engagement ot contacts 323 completes the circuit for thearmature 21 and separately excited field winding 3. 01 the drivingmotor. The engagement of contacts at connects coil 325 0! driving motoraccelerating switch MA across armature 21 ot the driving motor. Whenthevoltage of the driving motor rises to a predetermined point, switch MAoperates to engage contacts 326 and 321. Contacts 321 short-circuitresistance in series with the driving motor armature, applying full linevoltage to the driving motor to bring it to full speed. Contacts 325establish a circuit for coil 322 of driving motor starting switch MS,by-passing contacts "I and bridge member 320. The starting switch maythereupon be released and is returned to the position shown as by aspring. In contact with contacts 330. To stop the driving motor, switchS5 is turned counterclockwise, moving bridge 328 into position where itdisengages contacts 330. This breaks the circuit for coil 322 oi switchMS and switch MS drops out, disconnecting the driving motor from thesource oi supply. The driving motor starting switch MS is illustrated asprovided with an additional pair of contactsfli arranged toshort-circuit the generator armature and series field winding when themotor-generator set is not in operation. This may be provided oninstallations where it may be desired to operate the elevator car attimes without the levelling control.

The invention is particularly applicable for changing over existingresistance control installations, i; e., elevator installations in whichthe elevator motor is controlled by resistance in series with the motorarmature and resistance connected in the by-pass circuit for the motorammture. Such installations may be changed over to embody the inventionin a very simple manner by the addition of the small motor-gen oratorset and suitable mechanism ior controlling the operation of this set.

its many changes could be made in the above construction'and manyapparently Widely dili'crcut embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What claimed is:

1. In a control system Ior an elevator car in which the car is startedby connecting the hoisting motor for the car to a source of directcurrent with resistance in series with the motor armature andaccelerated by cutting this resistance out of circuit, and in which thecar is retarded by including resistance in series with said armature andconnecting resistance in parallel with said armature, a direct currentgenerator, means for driving the generator, means for causing saiddriving means to drive said generator at least while the car is inoperation, means for connecting the field winding of said generator tosaid source, levelling mechanism, means for disconnecting said hoistingmotor armature from said source and connecting it across the armature ofsaid generator to cause said generator armature to supply current to thehoisting m0- tor armature for the operation of bringing the car to anexact landing level under-the control of said levelling mechanism, and'meansresponthis position, bridge 328 remains in sive to the operationof said levelling mechanism goo ies source when the landing.

2. In a control system for an elevator car in which the car is startedby connecting the hoisting motor for the car to a source of direct. current with resistance in series with the motor ormature and acceleratedby cutting this resistance out of circuit, and in which the car isretarded by including resistance in series with said arinature andconnecting resistance in parallel with said car becomes level with thearmature, a direct current generator, driving means for the generator,means for causing said which the car is startedcy connecting the hoist=ing motor for the car to a source or direct cur-- rent with resistancein series with the motor armature and accelerated Soy cutting thisresistance out of circuit, and in which the is retarded by reincludingsaid resistance in series with said armature and connecting resistancein parallel with said armature, a direct current generator, drivingmeans for the generator, means for causing operation of said drivingmeans to drive said generator all the time the car is in service,icyelling niechanismand means responsive to the operation of saidlevelling mechanism :"or disconnecting said hoisting motor armature fromsaid source, for connecting the armature oi said hoisting motor acrossthe armature or said generator and for connecting the field winding ofsaid generator to said source to cause said generator armature to supplycurrent to the hoisting motor armature for the operation of bringing thecar to an exact landing level under the control of said levellingmechanism.

4. In a control system for an elevator car in which the car is startedby connecting the hoisting motor for the car to a source of directcurrent with resistance in series with the motor armature andaccelerated by cutting this resistance out of circuit, and in which thecar is retarded by including resistance in series with said armature andconnecting resistance in parallel with said armature, a direct currentgenerator, a driving motor'ior the generator, a manually operableswitch, means responsive to the operation of said switch for connectingsaid driving motor to said source to drive said generator, levellingmechanism, means for completing a local circuit in? cluding thearmature'of said generator and the armature of said hoisting motor inseries rela tion, and means for disconnecting said hoisting motorarmature from said source and for connecting the field winding of saidgenerator to said source to cause said generator to supply current tothe hoisting motor for the operation of hiringing the car to an exactlanding level under the control of said levelling mechanism.

5. In a control system for an elevator car in which the car is startedby connecting the hoisting motor for the car to a source of directcurrent with resistance in series with the motor armature andaccelerated by short-circuiting this resistance in steps, and in whichthe car is retarded by reincluding said resistance in series with saidarmature and connecting additional resistance in parallel with saidarmature and decreasing the amount of said additional resistance insteps; a direct current generator, the armature of said generator beingconnected in series relation with the hoisting motor armature; a motorfor driving said generator; and means for causing said hoisting motor tolevel the car with the landing at which. a stop is losing made, saidmeans comprising levelling mechanism, means for connecting the armatureof said generator and the armature of said hoisting motor in a localcircuit, means for disconnecting said hoisting motor armature from saidsource and means responsive to the operation of said levelling mechanismfor connecting the field winding of said generator to said source tocause said generator armature to supply current to the hoisting motorarmature for the operation of bringing the car to an exact landing levelunder the control of said levelling rnecl'lanisni.

ii. In a control system for an elevator car in which the car is startedby connecting the hoistlug motor for the car to a source of directcurrent with resistance in series with the motor armature andaccelerated by short-circuiting this resistance in steps, and in whichthe car is retarded by reincluding said resistance in series with saidarmature and connecting additional resistance in parallel with saidarmature and decreasing the amount of said additional resistance insteps, a direct current compound wound generator, the armature of saidgenerator being connected in series relation with the hoisting motorarmature; a motor iordr'iving said generator; means for causing saidhoisting motor to level the car with the landing at which a stop isbeing made, said means comprising levelling mechanism, means forconnecting the armature of said generator and the armature-of saidhoisting motor in series relation in a local circuit, means fordisconnecting sald hoisting motor armature from said source, and meansresponsive to the operation of said levelling mechanism for connectingthe field winding of said generator adapted for separate excitation tosaid source to cause said generator armature to supply current to thehoisting motor armature for the operation of bringing the car to anexactlanding level under the control of said levelling mechanism; means forcontrolling the efiectiveness of the series field winding of saidgenerator; and means for causing operation of said controlling means torender said series field winding effective during levelling.

7. In a control system for an elevator car in which the car is startedloy connecting the hoisting motor for the car to a source of directcurrent with resistance in series with the motor armature andaccelerated by short-circuiting thisresistance in steps, and in whichthe car is retarded by reincluding said resistance in series with saidarmature and connecting additional resistance in parallel with saidarmature and decreasing the amount of said additional resistance insteps; a direct current compound wound generator, the armature of saidgenerator being connected in series relation with the hoisting motorarmature; a motor for driving said generator; means for causing saidhoisting motor to level the car with the landing at which a stop isbeing made, said means comprising levelling mocha-- nism, means forconnecting the armature of said generator and the armature of saidhoisting motor in series relation in a local circuit, means fordisconnecting said hoisting motor armature from said source and meansresponsive to the operation of said levelling mechanism (or connectingthe field winding of said generator adapted for separate excitation tosaid source to cause said generator armature to supply current to thehoisting motor armature for the operation of bringing the car to anexact landing level under the control of said levelling mechanism; andmeans for rendering the series field winding of said generatorineflective except during levelling and full speed operation of saidhoisting motor.

8. In a control system for an elevator car in which the car is startedby connecting the hoisting motor for the car to a source of directourrent with resistance in series with the motor armature andaccelerated by short-circuiting this resistance in steps, and in whichthe car is retarded by reincluding said resistance in series with saidarmature and connecting additional re sistance in parallel with saidarmature and decreaslng the amount of said additional resistance insteps; a direct current compound wound generator, the armature of saidgenerator being connected in series relation with said additionalresistance so as to be connected across the hoisting motor armaturealong with said additional resistance; a motor for driving saidgenerator; means for causing said hoisting motor to level the car withthe landing at which a stop is being made, said means comprisinglevelling mechanism, means for excluding said additional re sistancefrom the parallel circuit for the hoisting motor armature therebyconnecting'the armature of said generator and the armature of saidhoisting motor directly in series in a local circuit; means fordisconnecting said hoisting motor armature from said source and meansresponsive to the operation of said levelling mechanism for connectingthe field winding of said generator adapted for separate excitation tosaid source to cause said generator armature to supply current to thehoisting motor armature for the operation of bringing the car to anexact landing level under the control of said levelling mechanism; andmeans for rendering the series field winding of said generatorineifective except during levelling.

9. In a control system for an elevator car; a

source of direct current; a direct current hoisting motor for the car;'a direct current generator; driving means for the generator; means forcausing operation of said driving means to drive said generator so longas the elevator car is in service; means for causing current to besupplied to said hoisting motor from said source for full speedoperation of the car; means for causing said hoisting motor to level thecar with a desired landing in stopping; and means for causing current tobe supplied to said hoisting motor by said generator at a low voltagefor the levelling operaiion.

10. In a control system for an elevator car; a source of direct current;a direct current hoisting motor for the car; a direct current generatorhaving a separately excited field winding; driving means for thegenerator; means for causing operation of said driving means to drivesaid generator at least when the elevator car is running; means forconnecting the armature of said hoisting motor to said source in serieswith re sistance to start the car; means for cutting out said resistanceto bring the car up to full speed means for including resistance inseries with said armature and foriconnecting additional resistance inparallel with said armature to slow down the car; and means for causingsaid hoisting motor to level the car with a desired landing in stopping,said levelling means comprising means for connecting said field windingof said generator to said source and means for disconnecting thehoisting motor armature from said source and connecting it across thearmature oi said generator to cause said generator armature to supplycurrent to the hoisting motor armature for the levelling operation.

11. In a control system for an elevator car;

- a source of direct current; a direct current hoisting motor for thecar; a starting resistance for said motor; a by-pass resistance for saidmotor; a direct current generator; driving means for the generator;means for causing operation of said driving means to drive saidgenerator so long as the elevator car is in service; means forconnecting the armature of said hoisting motor to said source in serieswith said starting resistance to start the car; means for cutting outsaid starting resistance to bring the car up to full speed;

means for reincluding said starting resistance in series wih saidarmature and for connecting said by-pass resistance in parallel withsaid armature to slow down the car; and means for causing said hoistingmotor to level the car with a desired landing in stopping, saidlevelling means comprising levelling switching mechanism, and meansresponsive to the operation of said levelling switching mechanism forconnecting the field winding of said generator to said source, fordisconnecting the hoisting motor armature from said source and forconnecting the armature of said generator directly across the armatureof said hoisting motor to cause said generator armature to supplycurrent to the hoisting motor armature for the operation of bringing thecar to an exact landing level under the control of said levellingswitching mechanism.

12. In a control system for an elevator car; a source of direct current;a direct current hoisting motor for the car; a starting resistance forsaid motor; a by-pass resistance for said motor; a direct currentgenerator, the armature of which is connected permanently in seriesrelation with the armature of said hoisting motor; driving means for thegenerator; means for connecting the armature of said hoisting motor tosaid source in series with said starting resistance to start the car;means for cutting out said starting resistance to bring the car up tofull speed; means for reincluding said starting resistance in serieswith said armatures and for connecting said bypass resistance inparallel with both arinatures to slow down the car; and means forcausing said hoisting motor to level the car with a desired landing instopping, said levelling means comprising, levelling switchingmechanism, and means responsive to the operation of said levellingswitching mechanism ior connecting the field winding of said generatorto said source, for disconnecting the hoisting motor armature from saidsource and for connecting the armature of said generator directly acrossthe armature of said hoisting motor to cause said generator armature tosupply current to the hoisting motor armature for the operation ofbringing the car to an exact landing level under the control of saidlevelling switching mechanism.

13. In a control system for an elevator car; a source, of directcurrent; a direct current hoisting motor for the car; a startingresistance for said motor; a by-pass resistance for said motor; a directcurrent generator, the armature of which is connected permanently inseries relation with the armature of said hoisting motor; driving meansfor the generator; means for connecting the armature of said hoistingmotor, with said bypass resistance in parallel with both armatures, tosaid source in series with said starting resistance to start the car;switching means for disconnecting said by-pass resistance from acrosssaid armatures and for cutting out said starting resistance to bring thecar up to full speed. and for reincluding said starting resistance inseries with saidarmatures and reconnecting said bypass resistance inparallel with said armatures to slow down the car; and means for causingsaid hoisting motor to level the car with a desired landing in stopping,said levelling means comprising means for connecting the armature ofsaid generator directly across the armature of said hoisting motor andfor disconnecting the hoisting motor armature from said source,levelling switching mechanism and means responsive to the operation ofsaid levelling switching mechanism for connecting the field winding ofsaid generator to said source to cause said generator armature to supplycurrent to the hoisting motor armature for the operation of bringing thecar to an exact landing level under the control of said levellingswitching mechanism.

14. In a control system for an elevator car; a source of direct current;a direct current hoisting motor for the car; a starting resistance forsaid motor; a by-pass resistance for said motor; a direct currentcompound wound generator, the armature of which is permanently connectedin series relation with the armature of said hoisting motor; drivingmeans for the generator; means.

for connecting the armature of said hoisting motor, with the armature ofsaid generator in series therewith and with said by-pass resistance inparallel with both armatures, to said source in series with saidstarting resistance to" start the car; switching means for disconnectingsaid bypass resistance from across said armatures and forshort-circuiting said starting resistance to connect said hoisting motorarmature in series with said generator armature directly to said sourceto bring the car up to full speed and for reincluding said startingresistance in series with said armatures and reconnecting said by-passresistance in parallel with said armatures to slow down the car; meansfor causing said hoisting motor to level the car with a desired landingin stopping, said levelling means comprising means for short-circuitlngall of said by-pass resistance to form a local circuit fcrthe armatureof said generator and the armature of said hoisting motor, means fordisconnecting the armature of the hoisting motor from said source,levelling switching mechanism and means responsive to the operation ofsaid levelling switching mechanism for connecting the generatorseparately excited field winding to said source, such field winding notbeing energized except during levelling, to cause said generatorarmature to supply current to the hoisting motor armature for theoperation of bringing the car to an exact landing level under thecontrol of said levelling switching mechanism; and means for renderingthe series field winding of said generator inefiective except duringlevelling and full speed operation of said hoisting motor. I I

15. In a control system for an elevator car; a source of direct current;a direct current hoisting motor for the car; a direct current compoundwound generator; driving means for the generator; means for connectingthe armature of said hoisting motor to said source in series withresistance to start the car; means for cutting said resistance out ofcircuit to bring the car up to full speed; means for connectingresistance in parallel with said armature to slow down the car; meansfor disconnecting the hoisting motor armature from said source; meansfor connecting the armature of said hoisting motor across the armatureof said generator; means for energizing the generator separately excitedfield winding; means for causing said-hoisting motor to level the carwith a desired landing in stopping with current supplied to the hoistingmotor by the generator, said levelling means causing the supply of current from the generator to the motor to be discontinued when the carbecomes level with the landing; and means for rendering the series.field winding of said generator effective "during-the levellingoperation.

' 16. In a control system for an elevator car; a

source of direct current; a direct current hoisting motor for the car; adirect current compound wound generator; driving means for thegenerator; means for connecting the armature of said hoisting motor withthe armature of said generator in series therewith to said source inseries with resistance to start the car; switching means for cuttingsaid resistance out of circuit to bring the car up to full speed and forincluding resistance in series with said armatures and additionalresistance in parallel with said armatures to slow down the ear; meansfor causing said hoisting motor to level the car uith a desired landingin stopping, said levelling means comprising means for disconnecting thehoisting motor from said source and for connecting it to the armature ofsaid generator and means for connecting the generator separately excitedfield windingto said source to cause said generator armature to supplycurrent to the hoisting motor armature for the levelling operation: andmeans for rendering the series field winding of said generator effectiveonly during levelling and full speed operation of said hoisting motor.

17. In a control system for an elevator car; a source of direct current;a direct current hoisting motor for the car; a starting resistance forsaid motor; a by-pass resistance for said motor; a direct currentcompound wound generator; driving means for the generator; means forconnecting the armature of said hoisting motor with the armature of saidgenerator in series therewith and said by-pass resistance in parallelwith both armatures to said source in series with said startingresistance to start the car; switching means for disconnecting saidby-pass resistance from across said armatures and for short-circuitingsaid starting resistance to connect said hoisting motor armature inseries with said generator armature directly to said source to bring thecar up to full speed and for reincluding said starting resistance inseries with said armatures and reconnecting said by-pass resistance inparallel with said armatures to slow down the car; means for causingsaid hoisting motor to level the car with a desired landing in stopping,said levelling means comprising means for disconnecting the hoistingmotor from said source and for short-clrcuiting all of said by-passresistance to form a local circuit for the armature of said generatorand the armature of said hoisting motor, and means for connecting thegenerator separately excited field winding to said source to cause saidgenerator armature to supply current to the hoisting motor armature forthe levelling operation; and means for rendering the series fieldwinding of said generator ineflective except during levelling and fullspeed operation of said hoisting motor.

- 18. In a control system for an elevator car; a source of directcurrent; a direct current hoisting motor for the car; a direct currentgenerator having a separately excited field winding; driving means forthe generator; means for connecting the armature of said hoisting motorto said source in series with resistance to start the car and forcutting out said resistance to bring the car up to iull speed; means forincluding resistance in series with said hoisting motor armature andresistance across said hoisting motor armature to slow down the car, thearmature of said generator being connected in series with the lastmentioned resistance across the hoisting motor armature; and

. means for causing said hoisting motor to level the car with a desiredlanding in stopping, said levelling means comprising means iorconnecting the generator separately excited field winding to said sourceand for disconnecting the hoisting motor from said source and cuttingsaid last mentioned resistance out of circuit.

19. In a control system for an elevator car; a source of direct current;a direct current hoisting motor (or the car; a direct current generatorhaving a separately excited field winding; driving means for thegenerator; resistance; means for connecting the armature oi saidhoisting motor to said source in series with said resistance to startthe car; switching means for cutting said resistance out of circuit tobring the car up to full speed; additional resistance; means forreincluding the first mentioned resistance in series with said hoistingmotor armature and for connecting said additional resistance across saidhoisting motor armature to slow down the car, the armature-oi saidgenerator being included in the circuit for said additional resistanceacross the hoisting motor armature in series relation with saidadditional resistance; and means for causing said hoisting motor tolevel the car with a desired landing in stopping, said levelling meanscomprising means for disconnecting the hoisting motor from said sourceand for connecting the armature of said generator directly across thearmature of said hoisting motor, and means for connecting the generatorseparately excited field winding to said source to cause said generatorarmature to supply current to the hoisting motor armature for theoperation of bringing the car to an exact landing level.

20. In a control system for an elevator car; a source or direct current;a direct current hoisting motor for the car; a starting resistance forsaid motor; a by-pass resistance for said motor; a direct currentcompound wound generator, the armature of which is connected in seriesrelation with said by-pass resistance; driving means for the generator;means for connecting the armature of said hoisting motor, with thearniature of said generator and said by-pass resistance in seriesconnected in parallel thereto, to said source in series with saidstarting resistance to start the car; switching means for disconnectingsaid bypass resistance and generator. armature from acrol said hoistingmotor armature and for short-circuiting said starting resistance toconnect said hoisting motor armature directly to said source to bringthe car up to full speed and for reincluding said starting resistance inseries with said hoisting motor armature and reconnecting said by-passresistance across said hoisting motor armature to slow down the car,said generator armature being reconnected in series with said by-passresistance across the hoisting motor armature; means for causing saidhoisting motor to level the car with a desired landing in stopping, saidlevelling means comprising means for short-circuiting all of saidby-pass resistance to form a local circuit for the armature of saidgenerator and the armature of said hoisting motor, means fordisconnecting the hoisting motor from said source, levelling switchingmechanism and means responsive to the operation of said levellingswitching mechanism for connecting the generator separately excitedfield winding to said source, such field winding not being energizedexcept during levelling, to cause said generator armature to supplycurrentto the hoisting motor armature for the operation of bringing thecar to an exact landing level under the control of said levellingswitching mechanism; and means for rendering the series field winding ofsaid generator effective only during the levelling 0! said car.

21. In combination, a motor of the direct current, rheostatic controltype having resistances in series and in parallel with the armature forspeed control, connections driving the motor from line current at normalspeed, a relatively small low voltage generator in series with themotor, and connections operating the motor solely by current from saidgenerator at low speeds.

22. In combination, a main motor, means for connecting the motor topower lines, a generator having .its armature permanently in series withthe motor, a circuit ior connecting the field oi the generator withpower lines, and automatic means opening said circuit when the motor, isconnected to the power lines.

23. In elevator operating apparatus, a motor. means to connect the motorto power lines for normal operation, an auxiliary generator permanentlyin series with the motor and having a field, leveling switches, andmeans controlled by the leveling switches for energizing the field inthe direction necessary to supply current in proper direction to themotor for leveling action and with said motor disconnected irom thepower lines.

24. In combination, an electric motor, means to connect the motor withpower lines for normal operation,'a relatively small generatorpermanently connected with the motor circuit, said generator having ashunt field, and means to energize said field, only while said motor isdisconnected from said power lines, for low speed operation of themotor.

25. In an elevator operating apparatus, a moe tor, power lines,connections from the power lines to the motor for normal operation ofthe motor at high speed and low speed, a relatively small generatorhaving its armature permanently included in said connections, and meansfor driving the motor solely by current from the generator tor levelingoperations.

ANTHONY PINTO. RAYMOND ALONZO WAI'I'E.

